Edexcel GCSE Geography A (1GA0) — The Physical Environment
Every time you turn on a tap, you expect water to flow, but for millions worldwide, this simple act is never guaranteed. Drought is a prolonged period of abnormally low precipitation leading to a shortage of water. It is a temporary extreme weather event, unlike an arid region, which is permanently dry.
There are different ways to classify these dry periods. Meteorological drought is defined by the degree of dryness compared to the normal or long-term average rainfall for a specific region. Hydrological drought occurs when water reserves in aquifers, lakes, and reservoirs fall below established statistical averages.
When the demand for water exceeds the available amount during a certain period, or when poor quality restricts its use, a region experiences water stress. Human activities can make this worse through positive feedback loops. For example, deforestation and overgrazing reduce soil moisture and evapotranspiration, which in turn reduces rainfall and worsens the drought.
The same lack of rain can cause a price rise in one country and a fight for survival in another. The impacts of drought depend heavily on a nation's wealth, infrastructure, and reliance on agriculture.
In developed countries like the USA (California), impacts focus on commercial agriculture and economic losses. California's 2011–2017 drought cost the agricultural industry US$2.7 billion in 2015 alone, but there were near zero direct human deaths. This is due to high resilience, meaning the capacity of a community to withstand and recover from a hazard using wealth and technology like the Central Valley Project.
In emerging and developing countries like Ethiopia and Namibia, impacts are survival-based due to high vulnerability. In Ethiopia, 85% of the population relies on rain-fed subsistence farming, leaving them highly susceptible to crop failure. This forces massive rural-to-urban migration, with over 250,000 people per year moving to cities seeking survival. During the 2015 drought, 10.2 million people required emergency food aid, and school absentee rates hit 60% as children spent hours fetching water.
Despite these differences, there are clear similarities in how ecosystems are affected. Both regions suffered severe environmental degradation, including increased wildfire risk, loss of vegetation, and high tree mortality. Both also experienced rising food prices and a loss of ecological resilience.
| Impact Type | Developed Country (California, USA) | Emerging Country (Ethiopia/Namibia) |
|---|---|---|
| Social | Mandatory 25% urban water restrictions. Food prices for fresh produce rose by 6%. | 435,000 children suffered Severe Acute Malnutrition. Disease outbreaks (cholera) due to contaminated water. |
| Economic | 17,100 agricultural jobs lost. US$1.7 billion state economy cost in 2021. | 40%–60% of livestock herds died. 50% to 90% of main crop production lost. Ongoing cost of US$1.1 billion per year. |
| Environmental | Over 100 million trees died. Groundwater over-extraction caused 60 cm of land subsidence. | Extreme desertification (Namibia lost 14.4 million acres of vegetation). High deforestation for fuelwood. |
How do geographers actually measure the true cost of a disaster? To understand why impacts differ, we must analyze quantitative data such as GNI per capita and the Human Development Index.
Developed countries face higher absolute economic losses (billions of dollars) but have low mortality rates. Emerging countries experience higher relative impacts, meaning the disaster destroys a larger percentage of their total wealth and causes severe food insecurity. Food security exists when all people have physical and economic access to sufficient, safe, and nutritious food.
| Indicator | Developed (California, USA) | Emerging (Ethiopia) |
|---|---|---|
| GNI per capita | High (>US$60,000) | Low (~US$1,025 - US$1,350) |
| Human Development Index Rank | 20th (Very High) | 176th (Low) |
| Main Impact Focus | Economic and job loss | Famine, mortality, and disease |
| Vulnerability Type | Economically vulnerable | Socially and biologically vulnerable |
In geography exams, you must be able to calculate the scale of these impacts using provided data.
1. Percentage Change Calculation This formula shows how much a value has grown or shrunk relative to its starting size.
Worked Example:
If Namibia's crop yield fell from 500 tons to 150 tons during a drought, what is the percentage change?
Step 1: Identify the values: Old Value = , New Value = .
Step 2: Substitute into the formula:
Step 3: Calculate the difference:
Step 4: Divide and multiply:
2. Growth Deficit Calculation Moderate to extreme droughts typically reduce GDP per capita growth by to globally. In Ethiopia, the 2015/16 drought caused a significant growth deficit.
Worked Example:
Ethiopia projected a real GDP growth of , but achieved only due to the drought.
Step 1: Target Growth = , Actual Growth = .
Step 2: deficit.
This 3.2 percentage point loss represents billions of dollars in lost economic potential.
3. Water Deficit Calculation This formula helps determine the physical lack of water in an environment.
For example, in California in 2021, a temperature increase caused an extra 3–4 inches of evaporative demand, severely increasing the water deficit.
Despite the harsh economic data, Ethiopia's direct mortality rate in 2015 was much lower than during the 1984 drought. This was due to improved social resilience through the Productive Safety Net Programme and faster international aid.
Students often confuse an arid region with a drought. Remember that an arid region is permanently dry as part of its climate, whereas a drought is a temporary extreme weather event.
In 'Compare' questions worth 4 or more marks, examiners expect you to explicitly state BOTH similarities and differences; use connective phrases like 'Similarly...' or 'In contrast to California's economic loss, Ethiopia suffered a social crisis.'
When asked to 'Analyze' socio-economic data, you must use the numbers provided in the figure to calculate percentage changes or state multiples (e.g., 'The USA's GNI is approximately 50 times higher than Ethiopia's') to secure AO3 marks.
Remember that developed countries experience higher absolute economic losses in billions of dollars, but developing countries experience higher relative impacts as a percentage of their total wealth and loss of life.
Drought
A prolonged period of abnormally low water supply (precipitation) leading to a shortage of water.
Arid region
A region with a climate that is permanently dry, whereas a drought is a temporary extreme weather event.
Meteorological drought
Defined by the degree of dryness (lack of rainfall) compared to the normal or long-term average amount for a specific region.
Hydrological drought
Occurs when water reserves in aquifers, lakes, and reservoirs fall below established statistical averages.
Water stress
When the demand for water exceeds the available amount during a certain period, or when poor quality restricts its use.
Commercial agriculture
Farming focused on the large-scale production of crops and livestock for profit, affecting global supply prices.
Resilience
The capacity of a community or ecosystem to withstand, recover from, and adapt to a hazard event (linked to wealth, technology, and governance).
Vulnerability
The degree to which a population or ecosystem is susceptible to, and unable to cope with, the adverse effects of a hazard.
Subsistence farming
Farming where nearly all produce is consumed by the farmer and family, leaving little or no surplus for trade.
Ecological resilience
The capacity of an ecosystem to absorb a disturbance and reorganize while retaining essentially the same function and structure.
GNI per capita
Gross National Income divided by the population, representing the average wealth per person in a country.
Human Development Index
An indicator used to measure a country's level of social and economic development.
Food insecurity
A state where people lack certain access to enough safe and nutritious food for normal growth and development.
Food security
When all people, at all times, have physical, social, and economic access to sufficient, safe, and nutritious food.
Put your knowledge into practice — try past paper questions for Geography A
Drought
A prolonged period of abnormally low water supply (precipitation) leading to a shortage of water.
Arid region
A region with a climate that is permanently dry, whereas a drought is a temporary extreme weather event.
Meteorological drought
Defined by the degree of dryness (lack of rainfall) compared to the normal or long-term average amount for a specific region.
Hydrological drought
Occurs when water reserves in aquifers, lakes, and reservoirs fall below established statistical averages.
Water stress
When the demand for water exceeds the available amount during a certain period, or when poor quality restricts its use.
Commercial agriculture
Farming focused on the large-scale production of crops and livestock for profit, affecting global supply prices.
Resilience
The capacity of a community or ecosystem to withstand, recover from, and adapt to a hazard event (linked to wealth, technology, and governance).
Vulnerability
The degree to which a population or ecosystem is susceptible to, and unable to cope with, the adverse effects of a hazard.
Subsistence farming
Farming where nearly all produce is consumed by the farmer and family, leaving little or no surplus for trade.
Ecological resilience
The capacity of an ecosystem to absorb a disturbance and reorganize while retaining essentially the same function and structure.
GNI per capita
Gross National Income divided by the population, representing the average wealth per person in a country.
Human Development Index
An indicator used to measure a country's level of social and economic development.
Food insecurity
A state where people lack certain access to enough safe and nutritious food for normal growth and development.
Food security
When all people, at all times, have physical, social, and economic access to sufficient, safe, and nutritious food.
